ISSN:1075-2617    

DOI:10.1002/psc.53

出版商:John Wiley&Sons, Ltd.    

年代:1996

数据来源: WILEY

摘要:

AbstractThe evaluation of peptide structures in solution is made feasible by the combined use of two‐dimensional NMR in the laboratory (NOESY) and rotating frames (ROESY), and by the use of molecular dynamics calculations. The present paper describes how both the NMR method and molecular dynamics calculations were applied to very rigid synthetic bicyclic peptides that are analogues of natural amatoxins. The NMR theory, which allows the estimate of interatomic distances between interacting nuclei, is briefly discussed. The experimental data were compared with those of known solid‐state structures. Three amatoxin analogues have been examined. Of these, one is biologically active (S‐deoxo γ[R] OH‐Ile3‐amaninamide) and its structure in the solid state has recently been worked out. The second and third analogues (S‐deoxo‐Ile3‐Ala5‐amaninamide andS‐deoxo‐D‐Ile3‐amaninamide, respectively) are inactive and their solid‐state structures are unknown. The data presented confirm the authors' previous hypothesis that lack of biological activity ofS‐deoxo‐Ile3‐Ala5‐ amaninamide is due to the masking of the tryptophan ring by the methyl group ofL‐Ala and not to massive

ISSN:1075-2617    

DOI:10.1002/psc.44.o

出版商:John Wiley&Sons, Ltd.    

年代:1996

数据来源: WILEY

摘要:

AbstractA complete series of terminally blocked, monodispersed homo‐oligopeptides (to the pentamer level) from the sterically demanding, medium‐ring alicyclic Cα,α‐disubstituted glycine 1‐aminocyclooctane‐1‐carb oxylic acid (Ac8c), and two Ala/Ac8c tripeptides, were synthesized by solution methods and fully characterized. The preferred conformation of all the oligopeptides was determined in deuterochloroform solution by IR absorption and1H‐NMR. The molecular structures of the amino acid derivative Z‐Ac8c‐OH, the dipeptidepBrBz‐ (Ac8c)2‐OH and the tripeptidepBrBz‐(Ac8c)3‐OtBu were assessed in the crystal state by X‐ray diffraction. Conformational energy computations were performed on the monopeptide Ac‐Ac8c‐NHMe. Taken together, the results obtained strongly support the view that the Ac8c residue is an effective β‐turn and helix former. A comparison is also made with the conformational preferences of α‐aminoisobutyric acid, the prototype of Cα, α‐disubstituted glycines, and of the other members of the family of 1‐aminocycloalkane‐1‐carboxylic acids (Acnc, withn=3, 5–7) investigated so far. The implications for the use of the Ac8c resi

ISSN:1075-2617    

DOI:10.1002/psc.43.o

出版商:John Wiley&Sons, Ltd.    

年代:1996

数据来源: WILEY

摘要:

AbstractHuman midkine (hMK), a novel heparin‐binding neurotrophic factor consisting of 121 amino acid residues with five intramolecular disulphide bonds, was synthesized by solution procedure in order to demonstrate the usefulness of our newly developed solvent system, a mixture of dichloromethane or chloroform and trifluoroethanol. The final protected 121‐residue peptide was assembled from two large fully protected intermediates, Boc‐(1–5 9)‐OH and H‐(60–121)‐OBzl, in CHL/TFE (3:1, v/v) using water‐soluble carbodiimide in the presence of HOOBt as coupling reagents. After removal of the protecting groups by HF followed by treatment with Hg(OAc)2in 50% acetic acid, the fully deprotected peptide was subjected to the oxidative folding reaction. The final product was confirmed to have the correct disulphide structure from its tryptic peptide mapping and to possess the same biological activities as those of the natural product. In order to clarify the active region of the hMK molecule, the N‐terminal and C‐terminal half domains [(1–59) and (60–121)] were also synthesized by the same procedure used for the hMK synthesis. The C‐half domain was confirmed to show the full pattern of bioactivities except for the neuronal cell survival activity, while the N‐half one showed

ISSN:1075-2617    

DOI:10.1002/psc.45.o

出版商:John Wiley&Sons, Ltd.    

年代:1996

数据来源: WILEY

摘要:

AbstractThe affinity‐based Nα‐amino protecting group tetrabenzo [a,c,g,i]fluorenyl‐17‐methoxycarbonyl (Tbfmoc) has been utilized as a hydrophobic probe to allow the simple, quick and highly effective isolation of a 76 residue cysteine‐containing protein (MCP‐1). The base‐labile Tbfmoc group can be removed under very mild conditions, which preserve the thiol‐con taining protein in the reduced state. Oxidative folding was then used to furnish the biologically active

ISSN:1075-2617    

DOI:10.1002/psc.46.o

出版商:John Wiley&Sons, Ltd.    

年代:1996

数据来源: WILEY

摘要:

AbstractThe pentapeptide Boc‐Val‐ΔPhe‐Gly‐ΔPhe‐Val‐OMe, containing two dehydro‐phenylalanine (ΔPhe) residues, has been synthesized and its structure investigated. In the crystalline state, the molecule adopts a right‐handed 310‐helical conformation stabilized by two intramolecular hydrogen bonds between CO of Val1and NH of ΔPhe4, and between CO of ΔPhe2and NH of Val5, respectively. NMR measurements are consistent with the presence of 310‐helical structures also in acetonitrile and dimethylsulphoxide solution: the distances between backbone protons estimated from NOE connectivities are in overall agreement with those observed in the solid state; the chemical shifts of the amide protons show the smaller temperature coefficients for the NHs that in solid state are involved in intramolecular hydrogen bonds. The CD spectra in acetonitrile, chloroform, methanol and dimethylsulphoxide display exciton couplets of bands corresponding to the ΔPhe electronic transition at 280nm; the sign of the bands is consistent with the presence of helical structures having a prevalent left‐handed screw sense. Addition of 1,1,1,3,3,3‐hexafluoro‐ propan‐2‐ol gives rise to the gradual appearance of a couplet of opposite sign, suggesting the helix reversal from left‐handed sense to right‐handed sense. The conformational behaviour is discussed on the basis

ISSN:1075-2617    

DOI:10.1002/psc.47.o

出版商:John Wiley&Sons, Ltd.    

年代:1996

数据来源: WILEY

摘要:

AbstractWe have synthesized and crystallized the cyclic peptide (Gly‐Aib‐Gly)2. Its structure has been determined by conventional X‐ray diffracti on methods. In the crystal it adopts a conformation with one β‐turn (type I) and its mirror image at the other side of the ring. All conformation al angles are similar to those reported for these amino acid residues. In particular the Aib residue has a conformation intermediate between α‐ and 310‐helical conformations. The ring is an adequate model for the β‐turn conformation. A molecule of formic acid is found in the crystal which shows a very short hydrogen bond with one of the glycine

ISSN:1075-2617    

DOI:10.1002/psc.48

出版商:John Wiley&Sons, Ltd.    

年代:1996

数据来源: WILEY

摘要:

AbstractSynthetic lipopeptides are showing promise as vaccine candidates, but until now it has been very difficult to prepare them in homogeneous form. We describe the synthesis and characterization of a new water‐soluble, four‐branched template with a built‐in lipophilic adjuvant (Pam3Cys). Through the use of oxime chemistry, we attached four copies of an unprotected influenza virus peptide and characterized the product (13kDa) by reversed‐phase HPLC and electrospray ionization mass spectrometry. Several other such constructions were made using the new template and different peptides. We seem to have a general method for making synthetic lipopeptides in homogeneo

ISSN:1075-2617    

DOI:10.1002/psc.51

出版商:John Wiley&Sons, Ltd.    

年代:1996

数据来源: WILEY

ISSN:1075-2617    

DOI:10.1002/psc.310020101

出版商:John Wiley&Sons, Ltd.    

年代:1996

数据来源: WILEY